The purpose of a door is to provide security, comfort and privacy. Doors can be made out of wood, metal, vinyl or hardboard and are rated for either interior or exterior use. Some exterior doors are constructed with an insulated core to improve energy efficiency. Other features may include decorative trim, a window or a peep hole.
To operate effectively, doors must open and close smoothly, according to their design. Many doors are hinged on one side and either swing open 90 degrees or 180 degrees (a half circle). Sliding doors and pocket doors move on tracks. French doors are two hinged doors that meet in the middle. True French doors have no framing member in the middle, but connect to one another.
Inspecting the doors on a property can sometimes provide clues to structural problems or merely minor deficiencies that are easily fixed. Doors should be checked to determine if they open and close properly, if the locking mechanisms work and if they have been hung in appropriate locations. Doors should not block light switches or swing open and closed on their own unless, like many storm doors, they are designed to be self-closing. Exterior doors should always be hinged on the inside.